基于透射谱的热木星大气组成的观测特征研究

热木星大气的观测研究在系外行星科学中扮演着重要角色，既影响着行星内部结构的决定，也可能提供关于行星形成的初始条件、形成机制与迁移历史的线索，但是目前对热木星大气性质的宏观了解还很缺乏，大部分认知都只聚集在少数特例上。本项目拟通过构建一个在平衡温度、行星质量、表面重力、主星金属丰度等物理参数上拥有大范围覆盖的热木星样本，采用地基望远镜长缝或者多目标光谱获取其凌星主食的透射谱，从而细致分析出各样本个例的大气组成情况。本项目将会对包括碱金属原子、TiO/VO分子、水分子、云霾在内的多种大气成分进行证认，检查引发逆温的光学吸收体，分析得到相对元素丰度、温度、压强等信息，并试图构建昼夜交界处大气的平均温度结构。通过对样本的统计分析，我们对热木星大气性质的了解将会进入崭新的高度，其大气组成的光谱特征随温度等多种物理参数的变化情况将会得到初步的分类。申请人的基础及早期预研的成功足以保证本项目顺利开展。

Observational study of hot Jupiters’ atmospheres plays a crucial role in the exoplanet science, which could impact the determination of planetary internal structures and provide us insight into the initial conditions, formation mechanism, and migration history of the planet formation and evolution process. However, the atmospheric properties of hot Jupiters are still poorly understood, which mostly come from a handful of benchmark planets. This project is proposed to investigate in detail the atmospheric compositions of hot Jupiters, which are strategically chosen as a sample that has a good coverage of physical parameters such as equilibrium temperature, planetary mass, surface gravity, stellar metallicity etc., using ground-based long-slit or multi-object transmission spectroscopy. We will survey several atmospheric constituents including alkali metal atoms, TiO/VO molecules, water molecule, clouds/hazes etc.， and examine the optical absorbers that cause the inversion in the temperature structure. We will derive the relative chemical abundances, temperatures, and pressures, and try to construct the temperature-pressure profiles for the terminator atmospheres. Based on the statistics of spectral features in our enhanced sample, our understanding of hot Jupiters’ atmospheric properties will rise to a new level, accompanied with the first preliminary observational spectral classification for hot Jupiters’ atmospheres according to various physical parameters (e.g. temperatures). This project is strongly supported by the ample experiences of the applicants and the success of pre-studies.